1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/bug.h>
3 #include <linux/io.h>
4 #include <linux/types.h>
5 #include <linux/kdebug.h>
6 #include <linux/signal.h>
7 #include <linux/sched.h>
8 #include <linux/sched/debug.h>
9 #include <linux/sched/task_stack.h>
10 #include <linux/uaccess.h>
11 #include <linux/hardirq.h>
12 #include <linux/kernel.h>
13 #include <linux/kexec.h>
14 #include <linux/sched/signal.h>
15
16 #include <linux/extable.h>
17 #include <linux/module.h> /* print_modules */
18
19 #include <asm/ftrace.h>
20 #include <asm/unwinder.h>
21 #include <asm/traps.h>
22
23 static DEFINE_SPINLOCK(die_lock);
24
die(const char * str,struct pt_regs * regs,long err)25 void __noreturn die(const char *str, struct pt_regs *regs, long err)
26 {
27 static int die_counter;
28
29 oops_enter();
30
31 spin_lock_irq(&die_lock);
32 console_verbose();
33 bust_spinlocks(1);
34
35 printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
36 print_modules();
37 show_regs(regs);
38
39 printk("Process: %s (pid: %d, stack limit = %p)\n", current->comm,
40 task_pid_nr(current), task_stack_page(current) + 1);
41
42 if (!user_mode(regs) || in_interrupt())
43 dump_mem("Stack: ", KERN_DEFAULT, regs->regs[15],
44 THREAD_SIZE + (unsigned long)task_stack_page(current));
45
46 notify_die(DIE_OOPS, str, regs, err, 255, SIGSEGV);
47
48 bust_spinlocks(0);
49 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
50 spin_unlock_irq(&die_lock);
51 oops_exit();
52
53 if (kexec_should_crash(current))
54 crash_kexec(regs);
55
56 if (in_interrupt())
57 panic("Fatal exception in interrupt");
58
59 if (panic_on_oops)
60 panic("Fatal exception");
61
62 make_task_dead(SIGSEGV);
63 }
64
die_if_kernel(const char * str,struct pt_regs * regs,long err)65 void die_if_kernel(const char *str, struct pt_regs *regs, long err)
66 {
67 if (!user_mode(regs))
68 die(str, regs, err);
69 }
70
71 /*
72 * try and fix up kernelspace address errors
73 * - userspace errors just cause EFAULT to be returned, resulting in SEGV
74 * - kernel/userspace interfaces cause a jump to an appropriate handler
75 * - other kernel errors are bad
76 */
die_if_no_fixup(const char * str,struct pt_regs * regs,long err)77 void die_if_no_fixup(const char *str, struct pt_regs *regs, long err)
78 {
79 if (!user_mode(regs)) {
80 const struct exception_table_entry *fixup;
81 fixup = search_exception_tables(regs->pc);
82 if (fixup) {
83 regs->pc = fixup->fixup;
84 return;
85 }
86
87 die(str, regs, err);
88 }
89 }
90
91 #ifdef CONFIG_GENERIC_BUG
handle_BUG(struct pt_regs * regs)92 static void handle_BUG(struct pt_regs *regs)
93 {
94 const struct bug_entry *bug;
95 unsigned long bugaddr = regs->pc;
96 enum bug_trap_type tt;
97
98 if (!is_valid_bugaddr(bugaddr))
99 goto invalid;
100
101 bug = find_bug(bugaddr);
102
103 /* Switch unwinders when unwind_stack() is called */
104 if (bug->flags & BUGFLAG_UNWINDER)
105 unwinder_faulted = 1;
106
107 tt = report_bug(bugaddr, regs);
108 if (tt == BUG_TRAP_TYPE_WARN) {
109 regs->pc += instruction_size(bugaddr);
110 return;
111 }
112
113 invalid:
114 die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
115 }
116
is_valid_bugaddr(unsigned long addr)117 int is_valid_bugaddr(unsigned long addr)
118 {
119 insn_size_t opcode;
120
121 if (addr < PAGE_OFFSET)
122 return 0;
123 if (get_kernel_nofault(opcode, (insn_size_t *)addr))
124 return 0;
125 if (opcode == TRAPA_BUG_OPCODE)
126 return 1;
127
128 return 0;
129 }
130 #endif
131
132 /*
133 * Generic trap handler.
134 */
BUILD_TRAP_HANDLER(debug)135 BUILD_TRAP_HANDLER(debug)
136 {
137 TRAP_HANDLER_DECL;
138
139 /* Rewind */
140 regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
141
142 if (notify_die(DIE_TRAP, "debug trap", regs, 0, vec & 0xff,
143 SIGTRAP) == NOTIFY_STOP)
144 return;
145
146 force_sig(SIGTRAP);
147 }
148
149 /*
150 * Special handler for BUG() traps.
151 */
BUILD_TRAP_HANDLER(bug)152 BUILD_TRAP_HANDLER(bug)
153 {
154 TRAP_HANDLER_DECL;
155
156 /* Rewind */
157 regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
158
159 if (notify_die(DIE_TRAP, "bug trap", regs, 0, TRAPA_BUG_OPCODE & 0xff,
160 SIGTRAP) == NOTIFY_STOP)
161 return;
162
163 #ifdef CONFIG_GENERIC_BUG
164 if (__kernel_text_address(instruction_pointer(regs))) {
165 insn_size_t insn = *(insn_size_t *)instruction_pointer(regs);
166 if (insn == TRAPA_BUG_OPCODE)
167 handle_BUG(regs);
168 return;
169 }
170 #endif
171
172 force_sig(SIGTRAP);
173 }
174
BUILD_TRAP_HANDLER(nmi)175 BUILD_TRAP_HANDLER(nmi)
176 {
177 TRAP_HANDLER_DECL;
178
179 arch_ftrace_nmi_enter();
180
181 nmi_enter();
182 this_cpu_inc(irq_stat.__nmi_count);
183
184 switch (notify_die(DIE_NMI, "NMI", regs, 0, vec & 0xff, SIGINT)) {
185 case NOTIFY_OK:
186 case NOTIFY_STOP:
187 break;
188 case NOTIFY_BAD:
189 die("Fatal Non-Maskable Interrupt", regs, SIGINT);
190 default:
191 printk(KERN_ALERT "Got NMI, but nobody cared. Ignoring...\n");
192 break;
193 }
194
195 nmi_exit();
196
197 arch_ftrace_nmi_exit();
198 }
199